Or he could just cancel his Righteous Fury which wouldn't end up being such a drastic dps loss compared to what you suggest.
---------- Post added 2013-05-07 at 10:19 PM ----------
Well if you're talking about a situation where you're less than 1 min into the fight it'll take too long for vengeance to catch up and there's little you can do.
Hand of Salvation or just taunting a few more times usually solves the problem of vengeance differences.